Layer the chicken thighs at the bottom of the slow cooker. Add sliced carrots, chopped celery stalks, and diced onion on top.

In a mixing bowl, combine chicken stock, au jus mix, chicken gravy mix, garlic powder, onion powder, and black pepper. Whisk until smooth.

Pour the gravy mixture evenly over chicken and vegetables in the slow cooker.

Secure the lid and cook on low for 6 hours or high for 4 hours.

Once done, allow the dish to cool slightly before serving.

Serve over mashed potatoes, rice, or with bread to enjoy the gravy.